Agreed.
You could bump flash the white and print the blue on top however. DC White usually has enough adhesion that getting some water out of the White shouldn't hurt the DC process in the dryer to a degree that it's noticeable. Watch out that you don't have the White beneath the darkest areas of the blue though, it might turn the blue pastel.
Sepping this in Illy you will have to stack/align two copies of the element with the two color grad in it. Set your gradients to the spot color, on both ends of the spectrum, going from 5-10% (or whatever your mesh will hold) to 100%. Next, set the top element to overprint. Last off, play with the gradient spectrum on each until you get some overlap going on. Finishing touch is to set the angle on one to be different than the other to avoid dot stacking out of the RIP.
Outputting the gradient right out of illustrator with blue on one end, white on the other will not work out well on press. It's a huge drag for me that you have to do this workaround but it's the sadly the most efficient way to do it if it's just a couple elements.
